because the queue itself serves no purpose. When a held page is freed,
inserting the page into the hold queue has the side effect of setting the
page's "queue" field to PQ_HOLD. Later, when the page is unheld, it will
be freed because the "queue" field is PQ_HOLD. In other words, PQ_HOLD is
used as a flag, not a queue. So, this change replaces it with a flag.
To accomodate the new page flag, make the page's "flags" field wider and
"oflags" field narrower.
Reviewed by: kib
sched_unpin() as they are functions static and inline. This way it
can do two dangerous things:
- Reorder instructions around both of them, taking out from the safe
path operations that are supposed to be (ie. per-cpu accesses)
- Cache the value of td_pinned in CPU registers not making visible
in kernel context to the scheduler once it is scanning the runqueue,
as td_pinned is not marked volatile.
In order to avoid both possible bugs explicitly, protect the safe path
with compiler memory barriers. This will prevent reordering and caching
by the compiler about td_pinned operations.
Generally this could lead to suboptimal code traversing the pinnings
but this is not the case as can be easilly verified:
http://lists.freebsd.org/pipermail/svn-src-projects/2012-October/005797.html
Discussed with: jeff, jhb
MFC after: 2 weeks
address passed from the bootloader, rather than using a hard-coded value.
Make FreeBSD announce itself on the LED display similar to other kernels.
Remove uses of the previous LED routines, which were under-used and only used
in drivers for what seem like debugging purposes, despite those drivers being
widely-tested.
Remove several inlines for accessing memory that duplicate other functions
which are now used instead, as they are now entirely unused.
the power save queue.
* introduce some new ATH_NODE lock protected fields, tracking the
net80211 psq and TIM state;
* when doing buffer transitions - ie, when sending and completing
buffers - check the state of the SWQ and update the TIM appropriately.
* when clearing the TIM bit, if the SWQ is not empty then delay clearing
it.
This is racy, but it's no less racy than the current net80211 power
save queue management code. Specifically, with multiple TX threads,
it's quite plausible that parallel state updates will race and the
TIM will be left in an inconsistent state. I'll address that in
a follow-up commit.
after a much reduced timeout.
Typically web servers close their sockets quickly under the assumption
that the TCP connections goes away as well. That is not entirely true
however. If the peer closed the window we're going to wait for a long
time with lots of data in the send buffer.
MFC after: 2 weeks
draft-ietf-tcpm-initcwnd-05. It explains why the increased initial
window improves the overall performance of many web services without
risking congestion collapse.
As long as it remains a draft it is placed under a sysctl marking it
as experimental:
net.inet.tcp.experimental.initcwnd10 = 1
When it becomes an official RFC soon the sysctl will be changed to
the RFC number and moved to net.inet.tcp.
This implementation differs from the RFC draft in that it is a bit
more conservative in the case of packet loss on SYN or SYN|ACK because
we haven't reduced the default RTO to 1 second yet. Also the restart
window isn't yet increased as allowed. Both will be adjusted with
upcoming changes.
Is is enabled by default. In Linux it is enabled since kernel 3.0.
MFC after: 2 weeks
especially in the presence of bi-directional data transfers.
snd_wl1 tracks the right edge, including data in the reassembly
queue, of valid incoming data. This makes it like rcv_nxt plus
reassembly. It never goes backwards to prevent older, possibly
reordered segments from updating the window.
snd_wl2 tracks the left edge of sent data. This makes it a duplicate
of snd_una. However joining them right now is difficult due to
separate update dependencies in different places in the code flow.
snd_wnd tracks the current advertized send window by the peer. In
tcp_output() the effective window is calculated by subtracting the
already in-flight data, snd_nxt less snd_una, from it.
ACK's become the main clock of window updates and will always update
the window when the left edge of what we sent is advanced. The ACK
clock is the primary signaling mechanism in ongoing data transfers.
This works reliably even in the presence of reordering, reassembly
and retransmitted segments. The ACK clock is most important because
it determines how much data we are allowed to inject into the network.
Zero window updates get us out of persistence mode are crucial. Here
a segment that neither moves ACK nor SEQ but enlarges WND is accepted.
When the ACK clock is not active (that is we're not or no longer
sending any data) any segment that moves the extended right SEQ edge,
including out-of-order segments, updates the window. This gives us
updates especially during ping-pong transfers where the peer isn't
done consuming the already acknowledged data from the receive buffer
while responding with data.
The SSH protocol is a prime candidate to benefit from the improved
bi-directional window update logic as it has its own windowing
mechanism on top of TCP and is frequently sending back protocol ACK's.
Tcpdump provided by: darrenr
Tested by: darrenr
MFC after: 2 weeks
the default retransmit timeout, as base to calculate the backoff
time until next try instead of the TCP_REXMTVAL() macro which only
works correctly when we already have measured an actual RTT+RTTVAR.
Before it would cause the first retransmit at RTOBASE, the next
four at the same time (!) about 200ms later, and then another one
again RTOBASE later.
MFC after: 2 weeks
with softupdates went away. Note that this does not fix the problem
entirely; I'm committing it now to make it easier for someone to pick
up the work.
Reviewed by: mckusick
support with ath(4) and VIMAGE.
Right now the VIMAGE code doesn't supply a default vnet context during:
* hotplug attach;
* any device detach.
It special cases kldload/boot time probing (by setting the context to
vnet0) but that doesn't occur when probing devices during a bus rescan -
eg, adding a cardbus card.
These will eventually go away when the VIMAGE support extends to providing
default contexts to hotplug attach/detach.
mbuf's by doing proper testing with M_WRITABLE().
In m_collapse() replace an incomplete manual check for M_RDONLY
with the M_WRITABLE() macro that also tests for shared buffers
and other cases that make a particular mbuf immutable.
MFC after: 2 weeks
We've got more cluster sizes for quite some time now and the orginally
imposed limits and the previously codified thoughts on efficiency gains
are no longer true.
MFC after: 2 weeks
from an unprotected u_int that reports garbage on SMP to a function
based sysctl obtaining the current value from UMA.
Also read back the actual cache_limit after page size rounding by UMA.
PR: kern/165879
MFC after: 2 weeks
doing small reads on a (partially) filled receive socket buffer.
Normally one would a send a window update every time the available
space in the socket buffer increases by two times MSS. This leads
to a flurry of window updates that do not provide any meaningful
new information to the sender. There still is available space in
the window and the sender can continue sending data. All window
updates then get carried by the regular ACKs. Only when the socket
buffer was (almost) full and the window closed accordingly a window
updates delivery new information and allows the sender to start
sending more data again.
Send window updates only every two MSS when the socket buffer
has less than 1/8 space available, or the available space in the
socket buffer increased by 1/4 its full capacity, or the socket
buffer is very small. The next regular data ACK will carry and
report the exact window size again.
Reported by: sbruno
Tested by: darrenr
Tested by: Darren Baginski
PR: kern/116335
MFC after: 2 weeks
reduce the initial CWND to one segment. This reduction got lost
some time ago due to a change in initialization ordering.
Additionally in tcp_timer_rexmt() avoid entering fast recovery when
we're still in TCPS_SYN_SENT state.
MFC after: 2 weeks
reduce the initial CWND to one segment. This reduction got lost
some time ago due to a change in initialization ordering.
Additionally in tcp_timer_rexmt() avoid entering fast recovery when
we're still in TCPS_SYN_SENT state.
MFC after: 2 weeks
audio devices. This endpoint gives clues to the USB host about the
actual data rate on asynchronous endpoints and makes the more
expensive USB audio devices usable under FreeBSD.
The Linux USB audio driver was used as reference for the
automagic shift of the received value.
MFC after: 1 week
warns about unused variables in this code, so always add -Wno-unused to
the warning flags. Why gcc on x86 *doesn't* warn about this, I will never
know. The code itself should probably be fixed at some point.
safe in some cases to reduce CCB priority after it was scheduled with high
priority. This fixes reproducible deadlock when command sent through the
pass interface while ATA XPT recovers from command timeout.
Instead of that enforce priority at passioctl(). libcam provides no obvious
interface to specify CCB priority and so much (all?) code specifies zero
(highest) priority. This change limits pass CCBs priority to NORMAL run
level, allowing XPT to complete bus and device recovery after reset before
running any payload.
